The Truth About Sun Exposure

We couldn't do without the sun. It keeps us warm, fuels photosynthesis so we have spinach to eat and helps our bodies make vitamin D. We couldn't see across the street without the sun. But it also has a dark side.

Do we even dare sunbathe these days? We asked the experts.

SUNSCREENS AND SPF

Q: Will sunscreens protect me?

A: They can help, the FDA says. But take their label claims with a large grain of salt. The FDA has been trying since 1999 to get sunscreen makers to stop using what it calls "unsupported, absolute and/or misleading and confusing terms such as 'sunblock,' 'waterproof'" and others. Some brands say "waterproof" on their front label even though their back labels say, "Rinse with water to remove." So don't count on "sunblock" to block the sun, and don't count on "waterproof" products to stay on in the water. Be sure to reapply often.

Q: What SPF should I use?

A: You need an SPF (sun protection factor) of at least 15, according to the Skin Cancer Foundation. Dr. Jonette Keri, a dermatologist at the University of Miami Miller School of Medicine, recommends an SPF of at least 30 if you're at the beach, pool or tennis court. "Most people don't put on enough," she says. It takes two shot glasses of lotion to cover the average bather, and most people put on only about half that amount. So the higher SPF can help. "The higher the better," she says.

A: No. An SPF rating measures a sunscreen's protection against UVB (ultraviolet B) rays but not against UVA (ultraviolet A) rays, which can also cause wrinkles and skin cancer. For UVA ray protection, check the sunscreen label for the ingredient avobenzone or mexoryl.

Q: When should I apply sunscreen?

A: Apply 30 minutes before getting into the sun so your skin can soak up your sunscreen, and reapply every 90 minutes -more often if you go in the water, sweat a lot or towel off.

AT THE BEACH

Q: Is it safe to go to the beach?

A: "I want my patients to have fun and go to the beach, but they should protect themselves as much as they can," says Keri. Wear sunscreen when you go in the water. When you get out, get under an umbrella.

Q: I can't lie out in the sun with my trashy novel?

"I don't want you to do that," says Keri. "People have in mind that a tan is healthy. It's not. We dermatologists are trying to change the culture - get people NOT to go out and lie in the sun to get a tan. We know a lot more about ultraviolet radiation than we used to. I think most of my colleagues would agree."

A: Very little, says Keri. A white T-shirt has an SPF of only about 3, she says. But you can buy sun-protective swimwear, coverups, hats, even long-sleeve shirts and pants. The clothing is impregnated with zinc oxide or titanium oxide, the same ingredients in many sunscreens. While sunscreen is measured in SPF (sun protection factor), clothing is rated in UPF (ultraviolet protection factor). Try stores like Target, Kmart and Walmart or Google "sun protective clothing."

Q: Can dark-skinned people get sunburns?

A: Dark-skinned people are less susceptible because the melanin that gives their skin its color absorbs UV radiation, Keri says, "but they can still burn."

Q: What about tanning lotions that bronze the skin?

A: They're OK, Keri says, as long as the active ingredient is dihydroxyacetone (or DHA), which reacts with dead cells on your skin to turn you tan. But the tan you get gives you protection up to only an SPF of 3, so it won't help much against the real sun. Some tanning creams include protective ingredients with SPFs of 15 or higher. But that lasts only about 90 minutes, not the duration of the tan, which is usually about five days.

Q: Can I get a safe tan at a tanning salon?

A: The Skin Cancer Foundation warns against them altogether. So does Keri: "They're just a way to try to convince consumers they're healthy when they're not," she says.

Q: I hear the human body needs vitamin D and gets it from unprotected exposure to the sun. Will I get enough if I take so many protective measures?

This is a matter of debate in the medical community. Some doctors, including rheumatologist James Dowd, author of the "The Vitamin D Cure," advise at least some unprotected exposure to the sun. The known benefits of vitamin D - which can be blocked by SPFs rated 8 or higher - include helping calcium build strong bones, and researchers have looked in the vitamin's role in staving off colon cancer, multiple sclerosis, diabetes and heart disease.

Dermatologists like Keri say the risks of damage from unprotected exposure outweigh the potential benefits, and that vitamin D can be obtained in foods and supplements. Good sources include salmon, mackerel, sardines, fortified milk or cereals like Kashi or Total.

The National Institutes of Health, pointing out that UV radiation is a carcinogen that accumulates over a lifetime, concludes: "It is not known whether a desirable level of regular sun exposure exists that imposes no (or minimal) risk of skin cancer over time."

There is no definitive answer, so you may want to consult your doctor.